Idle problem

Nistune topics specific to the 6802 cpu

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Russ84NA
Posts: 66
Joined: Fri Mar 31, 2006 11:36 am
Location: Ohio, USA

Idle problem

Post by Russ84NA » Mon Aug 26, 2013 5:02 am

I am running a 1984 300zx with a VG30 NA. It makes 223 HP at the wheels and runs great once I get it warmed up and out of idle.
All the air controls have been removed. The engine is 3.1 liter stroked engine with 12:1 compression ratio. I run it on 93 octane pump gas.
The car is strictly a track and autoX car.
I have had a problem with the idle since I built the engine in 2009. I set the idle at 1000 rpm's. This works fine for the cam that is in it.
I start the car and it starts and idles fine. At 35 degrees coolant temp the idle drops to 500 rpm's and I have to keep my foot on the gas until it reaches 55 degrees, then the idle goes back to 1000 and all is well.
I lived with this as I said for a couple years since I had to warm up the engine for the track anyway. Then the last event it died on a 360 degree corner in an autox event when I pushed in the clutch and downshifted to first.

I pulled a log and found that the A/F ratio was between 17 and 22 at idle. As soon as you got on the throttle the A/R ratio goes and stays in the 12 to 13 range.
I also discovered that the timing drops about 15 degrees to 25 degrees and flat lines there until the temps reach 55 degrees. Then it adds the 15 degrees back into the timing.
I have fixed the A/F ratio problem by adding fuel to the area of the fuel map that it was accessing. It is now idling at 14.8 A/F. The problem is that it still pulls the timing at 35 degrees and puts it back at 55 degrees. I have added timing to the timing map in the lower rpm row and the first two load columns where the maps are being accessed. It still does the same thing. I have also tried some of the enrichment charts that use coolant temps and either fuel or timing and it still does the same thing.
Can anyone put me in the right direction as to where to look to correct it?

raddy
Posts: 159
Joined: Mon Mar 16, 2009 9:52 pm

Re: Idle problem

Post by raddy » Mon Aug 26, 2013 7:28 pm

Hi there, try to check if you have avialable conditional warmup ignition timing table and conditions for it, this is common at ca18det for example....

Russ84NA
Posts: 66
Joined: Fri Mar 31, 2006 11:36 am
Location: Ohio, USA

Re: Idle problem

Post by Russ84NA » Mon Aug 26, 2013 10:20 pm

raddy wrote:Hi there, try to check if you have avialable conditional warmup ignition timing table and conditions for it, this is common at ca18det for example....
The only timing tables I have listed are: Dwell time, Dwell duty, crank advance, Idle/decel RPM timing, and Timing Advance
The crank advance and timing advance are temp related.
The crank advance is already showing more than enough advance in the 35 to 55 range and I have tried increasing the advance in that range in the timing advance table with no results.

Even increasing the values in the timing map in the 400 RPM range and in the 400 to 1200 range in the lower TP columns haven't effected it.
It seems that something else is controlling the timing in the 35 to 55 degree range as the timing goes from 39/41 degrees to a flat 25 degrees. Then at 55 degrees it returns to the 39/41 timing

Bernardd
Posts: 253
Joined: Thu Jan 26, 2006 3:20 am

Re: Idle problem

Post by Bernardd » Tue Aug 27, 2013 11:51 am

Hi Russ. Have you tried to change the warmup timing max? This constant is found just below the injector latency change version 0.12.11. I can't remember which way to adjust it but I changed those values when I ran my engine with that ecu.

Russ84NA
Posts: 66
Joined: Fri Mar 31, 2006 11:36 am
Location: Ohio, USA

Re: Idle problem

Post by Russ84NA » Tue Aug 27, 2013 2:39 pm

Bernardd wrote:Hi Russ. Have you tried to change the warmup timing max? This constant is found just below the injector latency change version 0.12.11. I can't remember which way to adjust it but I changed those values when I ran my engine with that ecu.
Bernardd, it's been a long time since we last "talked"

I have not done anything with those tables. I was reading through the documentation on them and they seem like they might be the ticket. There are three tables: Warmup timing TP max it is currently set at 40
Warmup timing RPM max is currently set at 4000
Warmup timing temp max. is currently set at 205
These settings are the default settings from the original base file for the 88 ECU. I think it is out of a NA car as there is not a daughter board. Of the three the temp max seems to be the most likely to effect my problem.
Any explanation on how these three charts work would be appreciated

Thanks

Russ

raddy
Posts: 159
Joined: Mon Mar 16, 2009 9:52 pm

Re: Idle problem

Post by raddy » Tue Aug 27, 2013 6:07 pm

Hi Russ. Mentioned tables (Warmup timing TP max it is currently set at 40
Warmup timing RPM max is currently set at 4000
Warmup timing temp max. is currently set at 205) are conditions tables that I mentioned before. By these conditions is using another table usually called warmup timing table, but maybe its not avialable with your address file, but I suppose that your ecu contain it. To avoid timing issues during warmup just change:
Warmup timing RPM max-set to 2000rpm
Warmup timing RPM min-set to 1500rpm
Warmup timing temp max-set to 30deg
Warmup timing temp min-set to 20deg
Warmup timing TP max-set to TP value that is just above TP at idle. For example, if TP at idle is 10, set it to 15.

with these setting you actually disabled using warmup timing table and your timing issue should be solved. If you can locate warmup timing table itself, than just change this timing values to any reasonable numbers and then its not neccessary to change conditional tables...

Russ84NA
Posts: 66
Joined: Fri Mar 31, 2006 11:36 am
Location: Ohio, USA

Re: Idle problem

Post by Russ84NA » Wed Aug 28, 2013 12:26 am

raddy wrote:Hi Russ. Mentioned tables (Warmup timing TP max it is currently set at 40
Warmup timing RPM max is currently set at 4000
Warmup timing temp max. is currently set at 205) are conditions tables that I mentioned before. By these conditions is using another table usually called warmup timing table, but maybe its not avialable with your address file, but I suppose that your ecu contain it. To avoid timing issues during warmup just change:
Warmup timing RPM max-set to 2000rpm
Warmup timing RPM min-set to 1500rpm
Warmup timing temp max-set to 30deg
Warmup timing temp min-set to 20deg
Warmup timing TP max-set to TP value that is just above TP at idle. For example, if TP at idle is 10, set it to 15.

with these setting you actually disabled using warmup timing table and your timing issue should be solved. If you can locate warmup timing table itself, than just change this timing values to any reasonable numbers and then its not neccessary to change conditional tables...
Raddy,
Thanks for the advice. You are correct about not having the Warmup timing table available in my address file. I have three of the five condition tables, the Warmup timing temp min and the Warmup timing Rpm min are not there.
Without those two min tables, I assume the minimum becomes the lowest RPM and the temp becomes 0 degrees.
Since my problem begins at 35 degrees, by setting the max table to 30 this should take the temp out of play. As for the RPM, my issue is between 500 and 1000 rpm's
I have attached a log file showing the problem. Based on the fact that I have only max condition tables would you still use the values you suggest. Also should the values be changed one at a time, do a run, then change the next one?

Thanks

Russ
Attachments
idle tune_2013-08-18_1150_05.csv
(1.4 MiB) Downloaded 84 times

raddy
Posts: 159
Joined: Mon Mar 16, 2009 9:52 pm

Re: Idle problem

Post by raddy » Thu Aug 29, 2013 12:00 am

Its OK to change all values at once, just play with them and check results. By the way, I think that your ecu contains also other mentioned tables, but they are not defined in the address file, otherwise it doesnt have much sense...But try to play with avialable values, with little luck you can solve your issue. I have lot of experience with this from ca18det, but here are all related tables avialable...

Russ84NA
Posts: 66
Joined: Fri Mar 31, 2006 11:36 am
Location: Ohio, USA

Re: Idle problem

Post by Russ84NA » Fri Aug 30, 2013 8:16 am

raddy wrote:Its OK to change all values at once, just play with them and check results. By the way, I think that your ecu contains also other mentioned tables, but they are not defined in the address file, otherwise it doesnt have much sense...But try to play with avialable values, with little luck you can solve your issue. I have lot of experience with this from ca18det, but here are all related tables avialable...
This one is kicking my butt. Mainly because the problem occurs at lower coolant temps and you have to let the engine cool off before you can try anything else.
I changed the constant warmup timing values. First I cut the temp value to 30 from 40 and the rev from 4000 to 2000 and set the TP at the column where the last cell was accessed on the log. Did a pull and the same thing happened. At 37* coolant temp the timing was pulled to 25 degrees and the idle fell off. AFR stays in the 13.8 to 15 range
Something happened and I had to stop the engine right after the timing was pulled at the 37* coolant temp. The timing had gone to 25*. I started the engine up and started the log again...the starting point was 39* coolant temp by the time I got the log going, but the timing was back at the 39*timing level like before it reached 37* coolant temp.
I let everything cool down and lowered the constant values again. this time the TP to 20 (lowest accessed column in the log). The RPM I set to 0 and the coolant temp to 15*. This should have taken what ever map they are controlling out of play.
Did the pull and the same thing happened at 37* the timing was pulled to 25*. I stopped the engine and reset everything Started it again and the timing came back to the 39* to 41* range.
Whatever map is controlling the timing seems to be reset by restarting the engine and lets a different map take over.
Any ideas on what to try next?

Timbo_021
Posts: 24
Joined: Thu Apr 16, 2009 10:02 pm

Re: Idle problem

Post by Timbo_021 » Fri Aug 30, 2013 9:01 pm

I have had this same problem for as long as I can remember on my 87 Z. I have learned to just deal with it because I've tried everything in Nistune and it just wont get any better. Although I have changed my dizzy assembly and it seems to be happier but that might just be in my head. Haven't had time to look into data yet as the engine is in bits at the moment..

Actually, just thinking about it. Do you have your O2 sensor plugged in and working? When I took my sensor out it did get a lot better.. I have no proof with data though, only driving when the engine is still cold.

Russ84NA
Posts: 66
Joined: Fri Mar 31, 2006 11:36 am
Location: Ohio, USA

Re: Idle problem

Post by Russ84NA » Sat Aug 31, 2013 4:09 am

OK, I have lowered the constant warmup tables to the point they would not allow the map to be in play. They were at the highest levels. This didn't have any effect on the problem.
I just did another pull with the 02 sensor unplugged (narrow band) Wide band was running. Still had no effect on the problem.
This is what I have. When the coolant temp is below 37* C the RPM's are about 900 to 1000, AFR is in the 14 to 15 range, Timing is between 47* and 42* (starts at 47 and drops to 42 as the temp rises. Battery Voltage is between 14.2 and 14.4
At 37* coolant temp the timing is pulled to 25* and remains there until 55*. RPM's drop from 900 to 300/400 range (engine will continue to run on its own). Battery Voltage drops off to 13.3. AFR remains in the 14.4 to 14.8 range.
The only thing that seems to change is the timing and the battery voltage. The battery voltage could be because of the lower RPM's.
The only other thing is, and I have to do another pull to verify this, is that once I hit 37* coolant temp and the timing is pulled. If I shut off the engine and re start it, the timing seems to be restored and all runs as before 37* and after 55* coolant temp.
This tells me that the ecu is accessing a warm up map and won't let go until the car is restarted. It also doesn't seem to have any effect on the engine when I am running on the track.
Final try...any ideas, otherwise I will have to just warm up the car and deal with the low RPMs until it warms up.
Thanks

Matt
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Re: Idle problem

Post by Matt » Sat Aug 31, 2013 7:25 pm

Post a log with all these parameters as well as last good tune and I will compare it against what I see here

Russ84NA
Posts: 66
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Location: Ohio, USA

Re: Idle problem

Post by Russ84NA » Sat Aug 31, 2013 11:45 pm

Matt,
I have attached the last log I did as well as the tune I used to do it. I am also attaching the bin file that I have been using for a number of years. Both run the engine fine once you are on the track. It is just the idle that I am trying to fix. The bin used with the log starts with 8-29-2013 the other starts with 8-14-09.
I am posting two additional logs. These are the same pull that was dropped or I stopped the engine for some reason. I restarted the engine and resumed logging the pull.
The first is from start coolant temp until it got to 37* and pulled the timing. The second starts at 39* and runs past the 55* coolant temp where the timing would be reinstated, but in this case when I restarted the engine at 39* the timing was restored and stayed all the way. Since the forum will only allow me to add three files I will add them in an additional message
Thanks

Russ
Attachments
8_14_09 new engine stock setting.bin
Bin used for several years. Only idle problem
(16 KiB) Downloaded 68 times
8-29-2013 idle-timing-AFR fixes 3RD.bin
New bin file attempt to fix idle problem
(16 KiB) Downloaded 87 times
_2013-08-30_Idle timing AFR fixs 3rd bin.csv
Log using new bin file
(712.29 KiB) Downloaded 81 times

Russ84NA
Posts: 66
Joined: Fri Mar 31, 2006 11:36 am
Location: Ohio, USA

Re: Idle problem

Post by Russ84NA » Sat Aug 31, 2013 11:48 pm

Matt,
The other log, split into two logs

Russ
Attachments
idle check raise rpm to increase temp 8-18-2013_2013-08-29_1251_11.csv
Restart at 39* until 55*+ coolant temp
timing restored
(413.44 KiB) Downloaded 89 times
idle check raise rpm to increase temp 8-18-2013_2013-08-29_1246_13.csv
First part of pull to 37* coolant temp
(266.79 KiB) Downloaded 75 times

Russ84NA
Posts: 66
Joined: Fri Mar 31, 2006 11:36 am
Location: Ohio, USA

Re: Idle problem

Post by Russ84NA » Thu Sep 26, 2013 11:54 pm

Matt,
Any luck?

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